This article is complementary to Barrie Russell ’ s excellent article and “ Mustang ” plan that will be available via our website in the near future . Barrie and I have done some soul-searching over this and agree that while it may be teaching some of you how to suck eggs , there ’ s always a steady stream of new chums who have not yet discovered the joys of fabricating with foam . This will be a series over the next few issues .
Firstly , there are only a few books on foam-cutting , but a ton of articles on the Internet . A couple of good books are : “ Radio Control Foam Modelling ” by David Thomas and “ Building with Foam ” by Keith Sparks . The Thomas book is more comprehensive and if I had to choose just one , then the Thomas book would be it .
But , please , if you are using a power supply other than an off-the-shelf power supply that is intended for foam cutting , GET YOURSELF AN RCD BEFORE ANYTHING ELSE !! It ’ s the cheapest insurance you will ever buy , and it can save you from your own carelessness , or not thinking for 0.1 second , as that ’ s all it takes to be electrocuted . Mitre 10 has the “ Buyright ” one for $ 13.24 and one other brand for about $ 16 ; Bunnings has one for about $ 15 and while I have not checked , I ’ m pretty sure that Placemakers will have one too .
Righto , here we go : I recently had a need ( see Barrie Russell ’ s Mustang plan ) to cut a sheet that tapers from 25 mm thick at one end to a mere 5mm at the other . Picture 1 shows the easy way to do this . Set up a hot wire above the bench with a 25mm tube at one end , and a 5mm drill at the other . Then just feed the foam underneath it like a woodworking thicknesser . Note that you don ’ t need to power up the whole length of wire , just the section that is doing the cutting .
Obviously , if you require a parallel sheet , just place the correct ( and same ) sized spacer under each end
Then , the next task is to cut out the fuselage profile , What you need is a “ foam jigsaw ” and one is easily made , just rig up the wire vertically , Picture 2 shows my setup . The lower end is locked into a plug in the bench , while the upper end is spring loaded to a ceiling hook . Once again , you only need to heat the part that does the cutting , note the red and black alligator clips attached where it matters .
To cut out channels for servo wires etc , a small shaped cutter is required . Picture 3 shows two of these . The wire is 16 awg Nichrome but stainless steel might work as well . The dowel handle is essential , not only to hold and guide the cutter , but also be aware that things ( including the leads ) get pretty warm .
Barrie Russell has covered normal bows quite well , but I find a small short bow quite convenient from time to time . Picture 4 shows one I converted from an old hand fretsaw . Note the nylon bush at one end to avoid shorting out the wire . Picture 5 shows the method I use for terminating and tensioning a normal 1 metre bow . I use . 020 ” Inconel lockwire , but Nichrome works , as does thinner MIG welding wire , or stainless steel if you can find it .
Then to cut out tapered wing panels . I used to do this with two templates and a “ helper ” trying to keep track at some roughly similar rate . Warning , if you use your wife / partner / SO for this , it has been reported that disharmony can result ! Sometimes it works out well , other times less so ..
Then a number of years ago , I stumbled across an article in “ Model Builder ” that was an epiphany .